F-15C product page math error of fuel difference?

[blkspade]

So I happen to be looking at the fuel section of the product page and realized that the numbers don't add up to what I was looking into earlier as a part of a separate annoyance. So the total internal fuel weight is 13,455 lbs at 2070 gallons, which aligns perfectly with JP4 @ 6.5 lbs/gal. However if you apply that same logic to a 610 gal drop tank you'd get 3,965 lbs as opposed to the 4072 lbs listed on the product page. Is this an error or an indication that the drop tanks are loaded with something other JP-4, while not matching up to what I could find for -5 or -8?

[blkspade]

It also appears this is the case in game as displayed by drop tank totals. While I typically don't fly with 3 drop tanks, there is still the issue where fuel is consumed from the center tank simultaneously with the wing tanks.